Time length of signal for a digital pin to capture it?

hi folks. wondering, how long signal need on arduino's digital pin capture it? trying capture signal pulses 600 ns (nanoseconds), short digital pin read it? how know?

also, read time vary among different arduino boards? i'm trying on arduino mega 2560 if helps. if mega can't capture 600 ns signal, there board can, or out of realms of arduino?

thanks!

600ns 8-9 clocks. digitalread() see 1 must read @ right moment.

however hardware supports interrupts on pins (2,3 uno) , more effort on every pin.

check documentation attachinterrupt()

when pulse arrives interrupt call function , in function can set variable (must volatile) can checked in main loop().

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